Relay



S t 11, 1934 D. D. KNOWLES RELAY Filed Jan. 6, 1931 /1 9-? fig. 3

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W/7'A/t55f5. INVENTOR 5. WI? DeweyD. Know/e5.

Patented Sept. 11, 1934 7' UNITED STATES PATENT; OFFICE RELAYApplication January 6, 1931, Serial No. 506,918 4 Claims. (01. 250-27)My invention relates to relays and has particular relation to relays ofthe type including electric-discharge devices.

In experimenting with relays of this type, I

5 have encounteredconsiderable trouble from the electrical propertiesinherent in the mechanical structure of the incorporatedelectric-discharge devices. These properties commonly have the sameeffect as resistances and capacities inherent in the geometry of thebase and the connections of the device. To provide a base andconnections having perfect insulating properties is, of course, out ofthe question. Consequently, apparatus must be provided for compensatingfor these properties.

A discharging device of the type, included in the relays to whichreference was made hereinabove, comprises a plurality of principalelectrodes and a control electrode disposed together in a partiallyevacuated chamber. Depending on the application of the device,-thechamber is or is not filled with an inert gas at a low pressure.

The control electrode is ordinarily located adjacent to one principalelectrode, and, in general, the distance between the parts of these twoelectrodes that are contiguous to each other is maintained substantiallyless than the meanfree-path of the electrons in the gas or in thevacuum.

The control electrode thus situated has the property of preventing theflow of a substantial current between the principal electrodes until thepotential, between it and its adjacent electrode is decreased to apredetermined value. The necessary variation in potential may beobtained in numerous ways. However, for the purposes of the presentinvention, 1 shall principally regard the variation as attained bycorresponding variations in the capacity of a regulating condenserconnected in an impedance network linking the control electrode and itsassociated electrodes.

Since the electrodes are ordinarily sealed into aglass container whichis, in turn, fastened into .45 a base through which the leads pass, acertain equivalent capacity and a certain equivalent impedance may beregarded as introduced by the imperfections in the insulating propertiesof the base.

The presence of the resistance and the capacity has the effect ofcausing adjustment of the regulating condenser because the potentialsbetween the principal electrodes and the control electrodes vary in bothmagnitude and phase in a very complicated way. Thus, it often happensthat, as the regulating capacity is increased, the device firstunexpectedly breaks down, by reason of the fact that the potentialbetween the control electrode ,and its associated electrode has reachedthe necessary value. As the capacity is further increased, the dischargeceases to pass between the main electrodes by reason of the fact thatthe phase shift, introduced by the interaction of the regulatingcapacity and the inherent capacity, has caused the potentials betweenthe electrodes 5 of the device to assume such relative values that thedischarge is blocked. Further increase in the capacity may cause furthershift in phase between the electrodes of the device and result in asecond excitation of the device. I have, moreover, found that, inaddition to the mechanical structure of the discharge devices, thenature of the impedance that is utilized in varying the condition of therelay plays an important role in producing transition points.

Thus, a photo-cell is often utilized to produce the varying impedance,and it is a well known fact that, as the illumination impinging thecathode of a photo-cell increases, the cell varies in the character ofits response from a capacity to a resistance. When the transition froman apparent capacity to an apparent resistance occurs, a deleteriousphase shift is introduced into the relay which causes a sudden change tooccur in its electrical properties. The sudden and unexpected changes inthe activity of the electricdischarge device are known as transitionpoints .or dead spots in its characteristic.

It is, accordingly, an object of my invention to provide apparatus forcompensating for the effects introduced by the inherent electricalproperties of the mechanical structure of the electrical dischargedevices incorporated in an electric-discharge relay.

Another object of my invention is to provide a relay of the typeincluding an electric-discharge device wherein transition points or deadspots in the characteristics of the electric-discharge device areeliminated.

A further object of my invention is to provide, in a relay of the typeincluding an electric-discharge device, means'for stabilizing theactivity or" the discharge device. 1

An ancillary object of my invention is to provide an electric-dischargedevice wherein provisions are incorporated for eliminating transitionpoints.

Another ancillary object of my invention is to provide a method fordetermining the magnitude of the electrical device utilized in stabiliz-110 o sistance is utilized ing a relay of the type incorporatingelectricdischarge devices.

Another ancillary object of my invention is to provide apparatus forreducing the phase-shift arising from the characteristics of theelectrical constants incorporated in a relay including anelectric-discharge device.

More specifically stated, it is an object of my invention to so regulatethe impedances between the electrodes of an electric-discharge deviceincorporated in a relay that transition points in the activity of therelay are substantially eliminated.

According to my invention, I provide a relay including anelectric-discharge device, of the type described hereinabove, wherein animpedance of predetermined character is connected between the controlelectrode and a principal'elem I have found that a partrode of thedevice. ticularly useful system is one wherein a resistance isconnected-in series with the impedance (in the particular case acapacity) that is varied to regulate the activity of the device, and,consequently, of the relay. However, other types of impedance than aresistance are usable and the choice of the'impedance, which I may terma stabilization impedance, depends upon the type of impedance wherebythe'activityof the relay is regulated. Thus, I have found that, if arefor regulation of the control electrode potential, a capacity may beutilized for stabilization.

As to the magnitude of the impedance that is necessary in producingstabilization, I have found that it is broadly of the order of thevarying imedance. A more concise methodof determining the actual valueof this impedance for any particular set up will be given in thefollowing discussion.

The novel features that I consider'characteristic of my invention areset forth with particularity in the appended claims.- The inventionitself, however, both as to its organization and its methodof'operation, together with additional objects and advantages thereof,will best be understood from the following description of a specificembodiment, when read in connection with the accompanying drawing inwhich:

Figure 1 is a diagram of an electric circuit in which my invention isincorporated, and,

Figs. 2 and '3 are graphs that will be utilized illustrating the methodof finding the magnitude of the impedance that is necessary to producestabilization.

The apparatus shown in the drawing comprises a power-supply source 1connected in serice with the primary 3 of a transformer 5 through whichpower is transmitted to an electric-discharge device 7,-preferably ofthe type described hereinabove. r

The cathode 9 of the device 7 is connected directly to one terminal ofthe secondary 11 of the power-transmission transformer 5, while theanode 13 of the device is connected to the remaining terminal of thesecondary 11 through a "current-limiting impedance 15.

The system shown in the View is applicable for many practical purposes.In particular, it may be utilized as a-general purpose-relay. In such acase, an electromagnetic relay 16 is ordinarily connected inthe-p'rincipal circuit of the device '7 and its contactors cooperate toopen or close a work circuit 18, depending on the condition ofthedevice. For certain purposes, I have also found that theglow producedwhen the device 7 transmits current to be of great utility. For example,the luminous flashes which can be produced as the condition ofexcitation of the device 7 is varied has rather wide applicability inthe signalling art.

The inherent electrical properties of the electric-discharge device areshown by broken lines and comprise a plurality pf capacitors .17 andresistors 19 connected between the control electrode 21 and theprincipal electrodes 9 and 13 of .the device 7.

,As is the case in the ordinary relay, an external impedance device 23is connected between the control electrode .21 of the device 7 and thecathode 9. A variable capacitor 25 in series with 1 an impedance device27, preferably a resistor, is

connected between the anode 13 and'the control electrode 21.

,As the capacitance of capacitor 25 is increased, the difference ofpotential between the anode 13 and the control electrode 21 isdecreasedand, when this quantity attains a predetermined lower limit,the tube 7 breaks down, and a current flows between its principalelectrodes 9 and 13., The impedance device 27 has the property 300 ofstabilizing the activity of the electric-discharge device.

If the impedance device 217 is not included, the complex phase shiftingand the variation in "voltage introduced by the interaction of theregulating capacitor and the inherent capacitances causes the transitionpoints in the activity of the device to which reference was madeherein.- above. I have found that, by including the impedance, thesephenomena are entirely eliminated.

In Fig. 2, the characteristic curve for a par:- ticular relay isplotted. The current between the principal electrodes .of the tubes isplotted as ordinates and the impedance X,utilized in producing thebreakdown of the tube, is plotted as abscissae. The graph shown is, ofcourse, symbolical ofany type of electric-discharge relay.

The curve has two branches 29 and 31 between which is a region 33 oflength G. 3 I

When the tube is broken down, as is indicated by the branch 29, anincrease in the impedance X causes a decrease in thecurre-nt This con--dition persists until the relative phase of gridanode and cathode-anodevoltages assumes such a value that the tube becomes deenergiz-ed. Thecurrent in-the tube is then substantially zero over a region G'of valuesof X, and begins to increase when the relative phases of the voltages onthe electrodes of the tube attain the requisite values, L as isillustrated in the branchBl.

I have found that, if an impedance Z is added in series with theimpedance X which regulates the activity of the tube, the magnitudeofthe gap 33 decreases, as is illustrated by the curve 335 35, in Fig. 3.The tubeioperates without transition points when the value of the addedimpedance is greater than the value at the. point. 37 where the curve 35and the axis of Z meet, As has been intimated above, this value pf .Z isof the order of the impedance X and varies from a fraction of a .megohmto a value of theorder of 100 megohms depending on the character of theimpedance X. I have found, however, that as a ,general rule an impedanceof the .crder of 3145 10 megohms will yield satisfactory results.

It is to -be noted that my invention has, in the above description, beenapplied to a specific system. Itis not my purpose to restricttheinvention to this specific system as it is apparent that 1150 it maybe applied to any relay of the type including an electric-dischargedevice. It may, in fact, be regarded as applying to the device itselfrather than to the relay, and the necessary impedance means may beaffixed to the device during its manufacture and may thus be included asa permanent element of the device. It is apparent that the impedance maybe located within the container of the electric-discharge deviceutilized in a particular relay.

Again, I have found that my invention may be applied to a relay of thetype wherein the current is interrupted by the variation of an impedancein the cathode and grid circuit of an electricdischarge device.

In a light control relay, I have recently found that, whereas apredetermined increase in the illumination reduces the relay to anunexcited state, a further increase in the illumination causes the relayto become energized. By adding a resistance in series with the varyingimpedance, which was, in the case question, a photo-cell, this effectwas entirely eliminated. It is to be noted that, in the above discussedlight-control relay, the transition point was probably caused by thechange in the nature of the response of the cell as the illumination onits cathode increased.

A further matter of some importance is the restriction of the device perso. My invention is apparently applicable to any device wherein anelectric discharge takes place between a plurality of electrodes. Thus,it has application to thermionic tubes, mercury discharge tubes andother vacuum and gaseous discharge tubes well known in the art.

However, it is well to point out that I have found that my invention hasspecific application to discharge devices of the type commonly known asgrid-glow tubes and specifically described above. In devices of thistype, it has accomplished a very useful purpose and has considerablyincreased the utility cf the tubes. My invention is, therefore, to beregarded as specifically applicable to tubes of any type.

Although I have shown and described certain specific embodiments of myinvention, I am fully aware that many modifications thereof arepossible. My invention, therefore, is not to be restricted exceptinsofar as is necessitated by the prior art and by the spirit of theappended claims.

I claim as my invention:

1. In a relay of the type including an electricdischarge device of thetype having a control electrode and a plurality of principal electrodes,said device exhibiting transition phenomena evidenced by transition gapsin its characteristic, and an impedance coupled between said controlelectrode and one of said principal electrodes for regulating theactivity of said device, a second impedance connected in a series withsaid network first impedance and with said control electrode and saidlast-named principal electrode and having a magnitude greater than themagnitude at which the transition gaps of said device substantiallyvanish.

2. In a relay of the type including an electricdischarge device of thetype having a control electrode and a plurality of principal electrodes,said device exhibiting transition phenomena evidenced by transition gapsin its characteristic and an impedance coupled between said controlelectrode and one of said principal electrodes for re 'ulating theactivity of said device, a resistance connected in a series network withsaid impedance and with said control electrode and said last-namedprincipal electrode and having a magnitude greater than the magnitude atwhich the transition gaps of said device substantially vanish.

3. In a relay of the type including an electricdischarge device of thetype having a control electrode and a plurality of principal electrodes,said device exhibiting transition phenomena evidenced by transition gapsin its characteristic and an impedance coupled between said controlelectrode and one of said principal electrodes for regulating theactivity of said device, a second impedance connected in a seriesnetwork with said first impedance and with said control electrode andsaid last-named principal electrode and having a magnitude of the orderof said activity-regulating means.

4. In a relay of the type including an electricdischarge device of thetype having a control electrode and a plurality of principal electrodes,said device exhibiting transition phenomena evidenced by transition gapsin its characteristic, and an impedance coupled between said controlelectrode and one of said principal electrodes for regulating theactivity of said device, means in a series network with said impedanceand with said control electrode and said last named principal electrodefor maintaining the total impedance in said network at a magnitudegreater than the magnitude at which the transition gaps of said devicesubstantially vanish.

DEWEY D. KNOWLES.

